Helicopters, and particularly small and medium helicopters, may be equipped with a skid type landing gear. Skid landing gears generally include two longitudinal skid tubes for contacting the ground and two cross tubes connecting the skid tubes to the body of the helicopter, although alternate designs are also possible.
Skid landing gears are generally designed with consideration of energy absorption during hard landings, stress levels in normal landings which should be low enough to ensure a satisfactory fatigue life and an appropriate stiffness to avoid critical ground resonance modes.
Cross tubes typically have a circular or rectangular cross-section, to facilitate bending of the cross tubes to the desired shape. The cross tubes are generally made from an extruded tube having a constant cross-section; as such modulation of the inertias of the cross-section to minimize the cross tube weight can generally only be performed by changing the thickness of the tube, which typically provides for limited inertia variations. Thickness variations are typically obtained through chemically milling of the cross tubes after being formed to the desired profile, however, chemical milling processes are generally not environmentally friendly.